/*
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package ch01;

import java.util.Scanner;

/**
 *
 * @author Administrator
 */
public class Sum2 {
    public static void main(String args[]){
       Scanner sc=new Scanner(System.in);
       float f1=sc.nextFloat();
       int a=sc.nextInt();//
       int b=sc.nextInt();
       
        
        int sum=0;
       for(int i=a;i<=b;i++){
           sum=sum+i;
       }
       //System.out.println(sum);
       System.out.println("sum="+sum);
       
    }
    
}
